I'm not too familiar with those kits, but I may be able to answer your questions.
I did discover when I first started brewing and used extract kits that hydrometer readings were not always accurate because there was a tendency to get wort stratification. If the Krausen (the foamy stuff on top) fell, then active fermentation should be close to completed, but the yeast still works for awhile after to "clean up" after itself. I got in the habit of leaving my beers in the primary for a week or two before racking off the yeast cake to a secondary. The exceptions are my wheats which I want a little cloudy, my Belgians that can take more time, or my imperial beers which take more time.
You could try a small sample of your beer, I've done that when there is a question about the quality of a brew. My method is to sanitize a glass shot glass and take a sample (if I'm dipping it, I'll sanitize my hand too, I use Starsan). A gravity reading of 1.040 will be undrinkably sweet. If that's the case, you will need to warm the brew to around 65-70 degrees F. Not sure what the Celsius temperature would be. If fermentation doesn't restart after a day, you'll probably have to pitch more yeast and maintain a warm temperature.
